Error "Your migration failed checking source credentials. Cannot connect to Drive API: Error:"unauthorized_client", Description:"Client is unauthorized to retrieve access tokens using this method.", Uri:"""
This error occurs in a migration to/from a G Suite or Google Drive environment when the necessary API access has not been granted.
To enable API Access, follow these steps.
Google has limited this setting to G Suite Super Administrators only.
- If migrating using the G Suite (IMAP) endpoint, use this guide to ensure the proper API scopes have been set up: Enable access to G Suite (IMAP) using OAuth 2.0
- If migrating using the G Suite (Gmail API) endpoint, use this guide to set up a project and to set the necessary scopes and API access within G Suite: Set up Google API for migrating mailboxes Please note that these steps also apply for Google Drive migrations.
- This step is required for both the Source and Destination Admin Portals when migrating from Google Drive to Google Drive. Please note that these steps also apply for Google Drive migrations as well.